Comprehensive N-glycosylation mapping of envelope glycoprotein from tick-borne encephalitis virus grown in human and tick cells

Abstract

tick-borne encephalitis virus (tBeV) is the causative agent of severe human neuroinfections that most commonly occur after a tick bite. N-Glycosylation of the tBeV envelope (e) glycoprotein is critical for virus egress in mammalian cells, but not in tick cells. in addition, glycans have been reported to mask specific antigenic sites from recognition by neutralizing antibodies. In this regard, the main purpose of our study was to investigate the profile of N-glycans linked to the e protein of TBEV when grown in human neuronal cells and compare it to the profile of virus grown in tick cells. Mass spectrometric analysis revealed significant differences in these profiles. High-mannose glycan with five mannose residues (Man 5 GlcNAc 2), a complex biantennary galactosylated structure with core fucose (Gal 2 GlcNAc 2 Man 3 GlcNAc 2 Fuc), and a group of hybrid glycans with the composition Gal 0-1 GlcNAc 1 Man 3-5 GlcNAc 2 Fuc 0-1 were confirmed as the main asparagine-linked oligosaccharides on the surface of tBeV derived from human neuronal cells. the observed pattern was supported by examination of the glycopeptides, providing additional information about the glycosylation site in the E protein. In contrast, the profile of TBEV grown in tick cells showed that paucimannose (Man 3-4 GlcNAc 2 Fuc 0-1) and high-mannose structures with five and six mannoses (Man 5-6 GlcNAc 2) were major glycans on the viral surface. the reported results complement existing crystallography and cryoelectron tomography data on the e protein structure and could be instrumental for designing carbohydrate-binding antiviral agents active against tBeV.

WITHDRAWN: Complete Genome Sequence of Unusual Strain of Zika Virus From West Africa

“…Therefore, it is important to note that the N-glycosylation site may be associated with avivirus virulence and neuroinvasiveness [12,13].…”

How relevant are in vitro culture models for study of tick-pathogen interactions?

“…In this regard, it has been reported that N-glycosylation of the TBEV envelope protein E affects protein trafficking and virus infectivity in mammalian cells but not in tick cells [84]. Moreover, a significant difference was observed in the mass spectrometric profiles of N-glycans linked to the E protein between TBEV grown in human neuronal and IRE/CTVM19 cells [85]. The nucleoprotein of CCHFV is characterized by a highly-conserved DEVD motif that is cleaved by caspase-3 during the induction of apoptosis in mammalian cells, and probably plays a role in apoptosis modulation [86].…”

New Cell Lines Derived from European Tick Species

“…ticks in the Mediterranean and Balkan regions. Several studies on TBEV have used (directly or indirectly) the existing I. ricinus cell lines derived from UK and German ticks [7,[55][56][57][58][59][60]; the new I. ricinus lines derived from Spanish ticks will add a new dimension to research on TBEV-vector interactions. D. reticulatus is also suspected to be a natural vector of TBEV [57,61], but in vitro investigations have been hampered by the lack of any cell lines from this species.…”